Cutting heads, such as those used in wire or sheet metal cutters, are essentially composed of two jaws pivotally attached to each other. A cutting blade is located on the inner portion of each jaw. The object to be cut is positioned between the jaws, in the cutting blade section, and the jaws are pivoted towards each other to cut the object.
In one known jaw assembly, the jaws pivot around a pin located in a hole at a central pivot point, and are held together by straps which are bolted to either side of each jaw. See FIG. 1. Alternatively, jaws held together by straps can pivot around a set of mating gears, as shown in FIG. 2.
The disadvantage of such arrangements is that the jaws tend to be unstable, because of tolerance between the pivot hole and the pivot pin, or because of tolerance in the gears. It should be noted that the size of the pivot hole, or the clearance between the gears, changes as the jaws are pivoted. This leads to additional instability unless the pivot hole, or the gears, are precisely machined. In addition, imprecision in the machining of the straps or the holes in the straps will change the distance between the jaws. This leads to further instability at the pivot, because changing the distance between the jaws changes the way the pin fits into the hole, or the clearance between the gears.
Instability at the pivot can lead to undesired wobble of the jaws about the pivot axis and an irregular cut. While more precise machining will prevent such instability, it leads to increases in cost. Thus, what is needed is a system which can stabilize the jaws in a cutting head without requiring high tolerance machining and the concomitant increased costs.